New undergraduate students arriving to study physics at the University of Bristol from 1975 onwards have all taken the same test of their knowledge and understanding of physics and mathematics. Many of the questions test knowledge of material that has been in the A-level syllabus for maths or physics throughout this period. The ability of incoming students to answer these questions declined significantly in the 1990s with average scores falling from around 75% up to 1990 to below 50% after 2000 against a background of increasing A-level grades of the entrants to the programme. It is suggested that changes in teaching and examination methods have caused students to be less able to carry out multi-stage calculations and that the introduction of modular examinations may have encouraged a culture where students tend to forget material learnt in previous modules. (Contains 1 table, 5 figures and 1 footnote.)